/*
 *  Copyright (c) 2018 The WebRTC project authors. All Rights Reserved.
 *
 *  Use of this source code is governed by a BSD-style license
 *  that can be found in the LICENSE file in the root of the source
 *  tree. An additional intellectual property rights grant can be found
 *  in the file PATENTS.  All contributing project authors may
 *  be found in the AUTHORS file in the root of the source tree.
 */

#ifndef COMMON_VIDEO_H265_PPS_PARSER_H_
#define COMMON_VIDEO_H265_PPS_PARSER_H_

#include "absl/types/optional.h"
#include "api/array_view.h"
#include "rtc_base/bitstream_reader.h"

namespace rtc {
    class BitBuffer;
}

namespace webrtc {

    // A class for parsing out picture parameter set (PPS) data from a H265 NALU.
    class H265PpsParser {
    public:
        // The parsed state of the PPS. Only some select values are stored.
        // Add more as they are actually needed.
        struct PpsState {
            PpsState() = default;

            bool dependent_slice_segments_enabled_flag = 0;
            bool cabac_init_present_flag = 0;
            bool output_flag_present_flag = 0;
            uint32_t num_extra_slice_header_bits = 0;
            uint32_t num_ref_idx_l0_default_active_minus1 = 0;
            uint32_t num_ref_idx_l1_default_active_minus1 = 0;
            int32_t pic_init_qp_minus26 = 0;
            bool weighted_pred_flag = 0;
            bool weighted_bipred_flag = 0;
            bool lists_modification_present_flag = 0;
            uint32_t id = 0;
            uint32_t sps_id = 0;
        };

        // Unpack RBSP and parse PPS state from the supplied buffer.
        static absl::optional<PpsState> ParsePps(const uint8_t* data, size_t length);

        static bool ParsePpsIds(const uint8_t* data,
            size_t length,
            uint32_t* pps_id,
            uint32_t* sps_id);

        static absl::optional<uint32_t> ParsePpsIdFromSliceSegmentLayerRbsp(
            const uint8_t* data,
            size_t length,
            uint8_t nalu_type);

    protected:
        // Parse the PPS state, for a bit buffer where RBSP decoding has already been
        // performed.
        static absl::optional<PpsState> ParseInternal(
            rtc::ArrayView<const uint8_t> buffer);
        static bool ParsePpsIdsInternal(BitstreamReader& reader,
            uint32_t& pps_id,
            uint32_t& sps_id);
    };

}  // namespace webrtc

#endif  // COMMON_VIDEO_H265_PPS_PARSER_H_